Using C6 glial tumor cells, L 5178Y cells and normal murine bone marrow cells as test systems, the objectives of this study will be to investigate the cellular sites of action of D-glucosamine which may be responsible for its selective toxicity in tumor cells and to assess the ability of this drug to selectively potentiate the antineoplastic activity of drugs which effect cellular DNA and glycoprotein synthesis. The influence of proliferative state of the cell population, position of cells in the cell cycle and position of cells in the population growth cycle on cell sensitivity to D-glucosamine toxicity will be studied. The effects of D-glucosamine on cell cycle progression will be analyzed. A study of the toxicity of effective combinations of D-glucosamine with other antitumor agents for tumor cells in comparison with normal murine hematopoietic tissue will be used to determine an in vitro "therapeutic index" for each drug combination, and is expected to indicate which of the drug combinations are suitable for testing in animal tumor models. The importance of the proposed research lies in its potential applicability to the chemotherapeutic treatment of human and animal tumors.